Field of the Invention
The present invention relates to a sheet conveyance apparatus and an image forming apparatus, and particularly to a configuration thereof for reducing an operational force for opening or closing an opening/closing member.
Description of the Related Art
Conventionally, an image forming apparatus such as a printer, a copier, or a printer includes a sheet conveyance apparatus that conveys a sheet by using a conveyance roller pair provided in a sheet conveyance path. The sheet conveyance apparatus includes a door serving as an opening/closing member that is opened to remove a jammed sheet in the case where, for example, a sheet is jammed in the sheet conveyance path.
An example of such a sheet conveyance apparatus is configured such that, to facilitate removal of the jammed sheet, one of the conveyance roller pair serving as a driven roller is provided in the door and is separated from the other of the conveyance roller pair serving as a driving roller when the door is opened. When the removal of the jammed sheet is finished and the door is closed, the driven roller abuts the driving roller.
An example of a conventional sheet conveyance apparatus includes a sheet conveyance path defined by a fixed guide plate and a movable guide plate. In the example of the conventional sheet conveyance apparatus, the driven roller and an elastic member for pressing the driven roller against the driving roller are attached to the movable guide plate. For example, Japanese Patent Laid-Open No. 5-213476 discloses a sheet conveyance apparatus including a link member swingably provided between a movable guide plate and an upper side cover serving as the door such that the driven roller abuts the driving roller in accordance with a closing operation of the door.
In this sheet conveyance apparatus, when the upper side cover is closed, the movable guide plate is pressed via the elastic member by a pressurizing arm serving as the link member and held at a position to define the sheet conveyance path and press the driven roller against the driving roller. When the upper side cover is opened, the pressure applied by the pressurizing arm is released, the movable guide plate is elastically moved in a direction to move away from the fixed guide plate together with the upper side cover, and thus the driven roller is separated from the driving roller. When the opened upper side cover is closed, the closing operation of the upper side cover is conveyed to the movable guide plate via the pressurizing arm, and thus the movable guide plate is moved toward the fixed guide plate and the driven roller is pressed against the driving roller.
In a conventional sheet conveyance apparatus, in the case where, for example, the driven roller is provided at a position away from an opening/closing center of the opening/closing member, the opening/closing member opens with a great force due to a repulsive force of the elastic member when opening the opening/closing member. To prevent this, the opening/closing member requires to be opened against the elastic force of the elastic member. In addition, when closing the opening/closing member, the opening/closing member requires to be closed against the elastic force of the elastic member. As described above, in the case where the elastic member is provided, an operational force required to open or close the opening/closing member becomes larger, and thus the operability thereof decreases.